Temperature dependence and electrical properties of dominant low-frequencynoise source in SiGeHBT

The temperature dependence and electrical properties of the dominant low-fr equency noise source in a SiGe HBT has been investigated, By employing a te mperature variation of the device to get a variation of the base or collect or current independently of each other, it is shown that the dominant noise source is strongly dependent on the collector current, but only weakly dep endent on the base current. A modified Ebers-Moll model is presented that a ccounts for the collector current dependence of the dominant noise source a nd simultaneously accounts for the temperature dependence of beta. Using th e modified Ebers-Moll model, the understanding of the physical positioning of the noise source is simplified.